Abstract Opioid abuse disorder (OAD) affects 2.1 million of Americans annually resulting in overdoses numbering in the tens of thousands and skyrocketing rates of mortality. In addition to its enormous social impact, OAD carries a multi-billion-dollar price tag that includes $78.5 billion, specifically for health care and other costs related to prescription opioid abuse and misuse. Although effective interventions exist, they are highly underutilized ? Currently less than 1-in-5 Americans with prescription OUDs receive treatment for their disorder, the $2.8 billion spent accounting for less than 4% of the financial resources consumed by mismanagement of prescription opioid use. As treatment programs expand to meet need, it is critical that they be able to offer comprehensive services to best support patient recovery. Among potential treatment options for OAD, medication-assisted treatment (MAT) for opioid addiction ? typically employing methadone, buprenorphine or naltrexone ? has been shown to reduce withdrawal symptoms and is associated with reduced overdose risk and improved maternal and fetal outcomes in pregnancy. Since the inception of medication-assisted treatment (MAT) for opioid addiction, drug testing has provided both an objective measure of treatment efficacy and a tool to monitor patient progress, however, current methods are ill-suited for use in drug treatment settings. Liquid chromatography?tandem mass spectrometry (LC?MS-MS) is highly sensitive, but the method is slow to yield results and requires tedious sample processing. Easy to use immunochromatographic test strips (ICS) are gold-standard reference methods for point-of-care settings, but they are non-quantitative and have limited multiplexing capacity. A multiplexing tool is desirable for monitoring MAT because patients with OUD may have multiple opioids in their system over the course of treatment including the primary addictive opioid, treatment opioid, and less desirable substitutes for the addictive opioid of choice. Recognizing this unmet need in addiction treatment settings for a simple, yet sensitive, instrument that can measure multiple opioids in clinical specimens, SensoDx conceptualized a drug of abuse testing-on-a-chip strategy that implements microfluidics technology for high-sensitivity detection of opioids. In previous work (Phase I studies), we developed and clinically tested a triplex assay targeting simultaneous quantitative determination of buprenorphine, cocaine and morphine in oral fluid for use in buprenorphine-assisted treatment. This Phase II project will deliver a set of milestones ? an optimized cartridge (precision, cost, size), expanded multiplexing capabilities to detection of seven drugs (buprenorphine, morphine, oxycodone, methadone, heroine, fentanyl, and cocaine), and pilot-scale clinical validation (in patients undergoing MAT) that will form the foundation and proof-of-concept for a prototype SensoDx Drug ScreenTM platform ready for design and fabrication finalization, GLP manufacturing and testing. The efforts will result in the commercial release of analyzer instrumentation, sampling devices and customized disposables for entry into the Lab-on-a- Chip market, valued at $4.23 Billion (in 2016) and expected to grow at a CAGR of 11% by 2022.